Mixedness Model MMM

Fig ure 9-7. A plug flow reactor with side entry. 

Equation 9-34 does not use an initial value of as a boundary eondition. Instead, the usual boundary eondition assoeiated with Equation 9-34 is 

The outlet eoneentration from a maximum mixedness reaetor is found by evaluating the solution to Equation 9-34 at = 0 = 

The analytieal solution to Equation 9-34 is rather eomplex for reaetion order n 1, the (-r ) term is usually non-linear. Using numerieal methods, Equation 9-34 ean be treated as an initial value problem. Choose a value for = C (0) and integrate Equation 9-34. If C (A.) aehieves a steady state value, the eorreet value for C (0) was guessed. Onee Equation 9-34 has been solved subjeet to the appropriate boundary eonditions, the eonversion may be ealeulated from Caouc = Ca(0). 

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Micromixing between these two extremes (partial segregation) is possible, but not considered here. A model for (1) is the segregated-flow model (SFM) and for (2) is the maximum-mixedness model (MMM) (Zwietering, 1959). We use these in reactor models in Chapter 20. 

In addition to these two macromixing reactor models, in this chapter, we also consider two micromixing reactor models for evaluating the performance of a reactor the segregated flow model (SFM), introduced in Chapters 13 to 16, and the maximum-mixedness model (MMM). These latter two models also require knowledge of the kinetics and of the global or macromixing behavior, as reflected in the RTD. 

The maximum-mixedness model (MMM) for a reactor represents the micromixing condition of complete dispersion, where fluid elements mix completely at the molecular level. The model is represented as a PFR with fluid (feed) entering continuously incrementally along the length of the reactor, as illustrated in Figure 20.1 (after Zwieter-ing, 1959). The introduction of feed incrementally in a PFR implies complete mixing... 

ASME CFSTR CFD CFM DIERS exp IR HA/AN HAZOP MM MMM American Society of Mechanical Engineers Continuous flow stirred tank reactor Computational fluid dynamics Computational fluid mixing Design Institute for Emergency Relief Systems exponential Infrared (spectroscopy) Hazard analysis Hazard and operability studies Michaelis-Menten Maximum-mixedness model... 

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